Diseases that cause dry and bitter mouth in the morning are: 1, oral mucosal dryness syndrome, which occurs mostly in women in their forties and fifties, due to immune dysfunction caused by damage to the salivary glands, reduced salivary secretion leading to extreme dryness in the mouth, burning sensation and taste disorders. 2, more than one tooth in the mouth has dental caries, periapical periodontitis, pulpitis, periapical inflammation of the wisdom teeth, periodontal disease, or a large area of the mucous membrane ulcers, which makes the inside of the mouth disease-causing bacteria The morning mouth is dry and bitter. 3, suffering from cholecystitis, cholelithiasis, cholestasis and other diseases. 4, eating too much at night, eating greasy, indigestible food, resulting in food accumulation, gastric fire caused by the morning mouth is dry and bitter. 5, suffering from chronic gastritis, gastric ulcer, gastric dyskinesia and other diseases that make indigestion, the food in the stomach for too long time caused by the mouth bitter. 6, suffering from chronic gastritis, gastric ulcer, gastric dysfunction and other diseases that make indigestion, food in the stomach inside the long time caused by bitter mouth.